During aircraft operations consisting of rapid engine transitions from low to high power levels, it is desirable to reduce the response time of the engine in order to achieve a required power. For this purpose, inlet mass flow can be increased by accelerating the gas generator of the engine, thereby increasing the engine's power. This may be achieved by a variety of techniques. For instance, a bleed valve may be actuated either actively or passively. However, active actuation of the bleed valve adds weight to the engine while passive actuation increases the gas path temperature and decreases the gas generator speed of the engine. The running line of the engine can alternatively be lowered to improve transient engine performance. This may however result in a decrease in the overall efficiency, an increase in specific fuel consumption, and maximum required operating gas generator speed of the engine while increasing the overall operating temperature thereof. Although casing treatment may also be used, this technique may lower the efficiency of the engine.
There is therefore a need for an improved method for controlling the transient power response of an engine.